Are you using microstrip? Basically, you can increase you substrate thickness in order to improve you bandwidth.
From an antenna theory viewpoint, the antenna size in relation to wavelength sets the achievable bandwidth. There's a theoretical limit for the maximal bandwidth respectively minimal Q that can't be exceeded. Increasing the substrate thickness will result in a larger patch size for the same center frequency.
any one help me how increase bandwidth of patch antenna using cst
My final project